Similarly, the choice of directive words is also concerned carefully by the teachers。 As can be seen from the transcript, the most frequently used words are “can”, “may”, and “could”, instead of “should”, “must” and “need to”。 According to Leech(2004)’s study, this tendency may be attributed to suppress or avoid overt claims to power and authority, because those modal verbs can reflect democracy。 This is also the same as what was mentioned in the above paragraph。Similarly, the choice of directive words is also concerned carefully by the teachers。 As can be seen from the transcript, the most frequently used words are “can”, “may”, and “could”, instead of “should”, “must” and “need to”。 According to Leech(2004)’s study, this tendency may be attributed to suppress or avoid overt claims to power and authority, because those modal verbs can reflect democracy。 This is also the same as what was mentioned in the above paragraph。